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Electric Cooking

Overview of Electric Cooking

The hot air which is emitted during cooking includes substances which have emanated from the foodstuffs themselves, as well as others derived from fats and oils used in the cooking process. Some of these are responsible for typical cooking smells whilst others may appear as smoke. A portion of this smoke may later condense to form greasy deposits of particulate matter in the oven itself and surrounding areas.

In a busy commercial kitchen it is often necessary to keep cooking fumes under control, for the following reasons:

  • To make the kitchen a more pleasant working environment
  • To improve the air quality in the dining area, if the building is open-plan
  • To prevent a build-up of greasy deposits which may constitute a health or fire risk
  • To reduce nuisance smells outside the building
  • To prevent flavour transfer from one type of foodstuff to another
  • To enable a building without an extraction system to be used as a kitchen

In a domestic situation cooking smells are generally more acceptable, however fumes from pyrolytic self-cleaning ovens can be very unpleasant and even dangerous.

Chemistry of fumes from Electric Cooking

Discover the risks of prolonged exposure to emissions in kitchens.

Cooking is a complex process involving both chemical reactions and phase changes. The difference between the two is that chemical reactions are usually not reversible and lead to the emissions of gases, whereas phase changes are only temporary and will reverse when the substances cool down. The resulting emissions from these phase changes are often referred to as ‘condensable particulate matter’ and comprise fats and oils which have become volatile during the cooking process then condensed back into liquids and solids after leaving the oven.

Breathing in cooking fumes over a prolonged period has been shown to have negative health effects. There are two main reasons for this. Firstly, certain chemicals which are emitted during cooking are toxic. Examples include aldehydes and alkanoic acids which cause irritation of the lungs, as well as polycyclic aromatic hydrocarbons and heterocyclic compounds which are carcinogenic.

The second problem is that cooking foods containing fat produces aerosols of fatty acids, which are also known as particulates. These can obstruct the small airways in the lungs and cause breathing difficulties and even in some cases pneumonia.

Discover the detail behind the catalysis of electric cooking.

Abatement of electric oven emissions

Catalytic converters are very effective at oxidising most of the organic gases and condensable particulate matter components of cooking fumes to carbon dioxide and water.

These reactions have double benefits: they improve air quality and also release heat energy from the fumes which would otherwise be wasted.

In order for the catalytic converter to be effective, the temperature of the gas passing through it needs to be at least 180°C (356°F) therefore this technology is most suited to enclosed cooking equipment such as ovens, charbroilers, fryers, chargrills and roasters . The most popular applications for catalytic converters in the commercial sector are rapid-cook combination ovens, as well as conveyor and pizza ovens.

A vital consideration for catalytic converters used in cooking appliances which involve gas recirculation is that the catalytic coating must be very well adhered to the substrate, otherwise it could flake off and contaminate the food.

The catalytic converter must also be made of materials which do not corrode in the moist atmosphere present in a cooking appliance. Ideally it should be installed in a location where it can be easily removed for cleaning.

Finally, cooking equipment equipped with catalytic converters must only be cleaned using approved chemicals, otherwise this may result in damage to the catalytic converter. Caustic cleaning products must never be used.

Quantifying cooking emissions

We have developed a dedicated facility to quantify emissions from cooking.

Whitebeam has developed a test kitchen with apparatus specifically designed to quantify organic cooking fumes. We measure the concentration of fumes extracted from the kitchen using an instrument called a flame ionization detector, which responds to combustible organic matter. After processing the data obtained by this instrument, we can calculate cooking fumes in a variety of formats e.g:

  • Mass concentration (mg/m3),
  • Mass per unit of food
  • Mass per unit of time

We can also use this test rig to investigate the durability of catalytic converters and to find out how this is affected by exposure to various oven-cleaning chemicals. Futhermore we can identify ‘secondary emissions’ i.e. those that result from contact between the catalytic converter and cleaning chemicals.

We use this test rig for our own R&D purposes, but we are also happy to use it and the expertise we have developed to undertake commercial projects for clients and interested parties.

The limits for oven emissions

We can help our customers to get their emissions in line with the standards.

Regulations are in place in many jurisdictions to deal with the air quality implications of commercial cooking. These regulations are usually focused on particulate matter, smells or sparks.

Commercial ventless ovens sold in the US need to pass a test to determine their condensable particulate emissions. The test, which follows a procedure known as EPA202, involves cooking a succession of pepperoni pizzas over an eight-hour period, during which the average particulate emissions from the oven must not exceed 5mg/m3.

A leading testing and certification body in the US is the Underwriters’ Laboratory, now abbreviated to ‘UL’. The UL puts ovens into various categories, one of which is referred to as ‘KNLZ’ for ‘commercial ovens with integral systems for limiting the emissions of grease laden air’. The UL’s test standard for this category of ovens is referred to as UL710B.

Another standard which is applicable to commercial ventless ovens sold in the US is known as ‘ANSI/NFPA96’. ANSI is the American National Standards Institute whilst NFPA stands for National Fire Protection Association, which has an interest in preventing kitchen fires caused by the build-up of particulate matter. Again, the limit for particulate emissions set by this standard is 5mg/m3. Achieving such low levels of particulate emissions generally requires the use of a catalytic converter.

Note: This website does not claim to be a definitive or up to date source of information on regulations and interested parties are advised to make their own enquiries.

Catalytic converters for electric ovens

We offer a range of catalytic converters to reduce fumes from electric ovens.

Catalytic converters installed in commercial electric cooking appliances are usually based on metallic honeycombs, which give the best performance in a compact space, without causing too much pressure drop. However, ceramic honeycombs are sometimes used as well, and these may be advantageous if they are located in the microwave zone.

One of the key requirements of a catalytic converter designed for a cooking appliance in which the air recirculates is that the coating adhesion must be excellent, otherwise the coating may fall off and contaminate foodstuffs during cooking. It is also essential that the catalytic converter materials are resistant to corrosion.

Find out more about the options here: